Means for sharpening serration cutters



April 1, 1958 A. JANTZ 2,828,585

MEANS FOR SHARPENING SERRATION CUTTERS Filed Dec. 5, 1956 3 Sheets-Sheet l INVENTOR.

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April 1, 1958 A. JANTZ 2,828,585

MEANS FOR SHARPENING SERRATION CUTTERS Filed Dec. 5, 1956 3 Sheets-Sheet 2 m mm l. II mw ww wk mu w @m a April 1, 1958 A. JANTZ 2,828,585

MEANS FOR SHARPENING SERRATION CUTTERS Filed Dec. 5, 1956 3 Sheets-Sheet 3 INVENTOR,

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MEANS FOR SHARPENLNG SERRATIGN CUTTERS Alvin Jantz, Newton, llans.,-assignor to Boeing Airplane (Iompany, Wichita, Kane, a corporation ofDelnware Application December 5, 195:5,Serial No. 626,337

Claims. (Si. 51--105) ing of serration cutters.

Automatic threadgrinders adapted to cut and sharpen helicalthreads are presently in use and have resulted in large savings. However, no means have been provided to perform similar automatic operations on serration cutters. A serration cutter may be definedas a cutter for cut ting serrations having teeth disposed in a plurality of rows, the rows being parallel to the cutter axis, and the teeth in the rows being oriented in circumferential files substantially at right angles to the cutter axis. To sharpen the serration cutters on conventional thread grinders before this invention, it was necessary to manually reset the grinder for each circumferential file, the number of settings depending on the number of files.

The thread grinders are normally adapted to grind helical threads by rotation of a workpiece between head and tail stock center spindles by a dog connected to .a rotating head member. While the workpiece is rotated, the head and tail stocks are advanced laterally of the periphery of a grinding wheel whereby the actual cut is in a helical pattern.

The objectives of my invention include: to devise improved means for sharpening serration cutters; to provide means for automatically sharpening such cutters; to provide an attachment for a standard thread grinder to automatically grind such cutters; and to provide the above in an economical structure which is accurate and efficient of operation and preferably automatic after initial setting.

My invention will be best understood, together with additional objectives and advantages thereof, from a reading of the following description, read with reference to the drawings, in which:

Figure l is a perspective view showing certain components of a thread grinder and showing a specific embodiment of my invention installed in the thread grinder;

Figure 2 is an enlarged side elevation of a portion of the head assembly incorporating cam means, portions being broken away and shown in section;

Figure 3 is a fragmentary, enlarged side elevation of the cam and cam follower of said cam means;

Figure 4 is a side elevation of the head stock assembly with portions broken away and shown in section and with portions of the head stock being shown in phantom or omitted;

Figure 5 is an enlarged, fragmentary view taken on line 5-5 of Figure 4; and

Figure 6 is an enlarged, fragmentary view of portions of a serration cutter and grinding wheel.

Figure 1 shows my invention as incorporated in a conventional automatic thread grinding machine. he structure shown follows that of the model TG-l245 thread grinder of lones & Lamson Machine Company, pringfield, Vermont. However, the invention is adaptable to other thread grinders on the market. Only a brief description will be given of tie thread grinder as such machines are well known to the art.

The machine includes a base 10 and a table 12 which is mounted for rectilinear movement on the base. This movement, together with rotation of the workpiece,

causes a grinding wheel 14 to normallymakeahelical cut on the workpiece. Means are provided .to power the assembly for these movements which are closely controlled so that an exact type of threaded body can be produced. The same powermeans and controls .can .be used for automatic operation when the thread grinder is adapted to cut serration cutters ashereafter described.

Head and tail stocks 16, 18 are mountedon :table 12 and are adjustable in position to accept varioustypes of work. Head and tail center spindles 2.0, .22 rotatably support the work and the tail center spindle J22.is.slidably mounted in tail stock '13 and is urged against the work by a compression spring 24. .A rotatinghead member .30 is connected to the work by a dog 32 attached to :an adjustable driving face plate or fixturefie.

Figure 4 shows in simplified, semidiagramrnatic .form some principal components of the head assembly. Rotating head member 30 is attached to a tubular lhead member 36 which is rotatably supported by bearings :33, 4i). A gear 42 is secured to tubular member .36 and is driven by a spur gear d i-attached-to a drive shaft 436.

The tubular head member 36 is provided in this machine principally so that work too long to normally be supported bet. can the head and tail stocks maybe inserted through member .35 to position an inner end portion in the normal location of a workpiece. Although my structure can be adapted to machines .not having this hollow head member, its presence is convenient for the installation of my invention. v

A housing 5:"? is frictionally secured in tube 3l6jby having a relative taper therebetween. Head center spindle 2% is slidably mounted in housing 5%. An oil seal is formed on the inner end by theresilientwasher 52 and a backing ring 54 secured by screws 55. A split ring "58 is secured on spindle 2b by a clamping bolt 6% and ring 58 carries a cam follower 62. Cam follower 62 is arodshaped body secured as by welding or brazing in a V- groove seat 61 formed in a boss 63 on ring 58. An *end plate 64 is secured to the-outer end of housing by bolts 66 and an oil seal is formed by a resilient washer "68 having a backing ring '71? secured thereto by rivets "i2. 7

Plate at carries an annular cam Cam 74 has a single rise 76 and the cam makes a straight line progression between the start and the peak of the rise. The cam is formed to exactly rctrogressively compensate for-the movement of table 12 relative grinding wheel 14 during eacr rotation of rotating head member '39 so that the serration cutter '78 is held in a fixed position longitudi nally of base ill. When foil wer'dii strikes 'rise 76 the cutter is moved the full distance that the table has moved relative the grinding wheel during that rotation.

in Figure 5, cutter 73 is shown in full lines in the position where grinding wheel i4 is engaging between teeth in one row 819 of the teeth. When cutter 7b is originally positioned it is located so that the cutter teeth will be in the position shown in dotted lines inFigure 5 when follower 62 strikes rise 76 so that the teeth will clear the grinding wheel during this relative movement. 'The advancement of cutter 73 by the action of, cam 74 is equal to the space x (Figure 6) between the circumferential files of teeth 89.

Head spindle 2!? has sliding movement relative head stock it? during each rotation and follower 62'is pressed the articulated end 90 in position but the and may be manually forced into and out of engagement with the bifurcation 92 of a bracket 94 secured to head stock 16 by a bolt 96.

The operation of my invention is as follows: serration cutter 78 is mounted between head and tail spindles 2%, 22. The cam plate 64 used has a cam rise 76 equal to the space 2: between circumferential files. may be interchanged according to the cutter to be sharpened. The thread grinder is set to advance table 12 relative base 10 a distance equal to x during each rotation of rotating head member 30. Cam rise 76 is located to be struck at the dotted line position of the serration teeth shown in Figure 5 of the drawings so that the grinding wheel may be passed. When other parts are located, then the pivotal end 90 of lateral arm 82 is engaged in the bifurcated bracket 94. These settings being accomplished, the machine will automatically grind the serra tion cutter and will consecutively locate grinding wheel 14 in line with each space between circumferential files of the serration teeth.

The standard thread grinding machine has a radial relieving attachment which reciprocates the grinding wheel toward and away from the workpiece. This attachment will not be described as it is well known and is used in cutting taps. The function of the attachment is to cut more deeply at the rear side of the tooth than at the forward edge so that the tooth may perform a cutting function. This radial relieving attachment is used in cutting the present serration cutters and is set according to the number of teeth on the cutter to obtain radial relief.

Having thus described my invention I do not wish to be understood as limiting myself to the precise details of construction shown, but instead wish to cover those modifications thereof which will occur to those skilled in the art from my disclosure and which fairly fall within the scope of my invention, as described in the following claims.

I claim:

1. Means for adapting a thread grinder to grind a serration cutter in which teeth disposed in a plurality of rows are oriented in circumferential files substantially at right angles to the cutter axis, the thread grinder being normally adapted to grind helical threads by rotation of a Workpiece between head and tail stock center spindles by a dog connected to a rotating head member while the head and tail stocks and a grinding wheel have relative movement whereby the workpiece is advanced laterally of the wheel periphery, comprising: a housing secured in said rotating head member to rotate therewith, said head center spindle D being slidably mounted in said housing and means connecting between said head spindle and a portion of said head stock holding said head spindle against rotation, said tail stock having spring means positioned to act on said tail center spindle and annular cam means in said housing acting between means in said housing and means on said head spindle pressed into engagement by said spring means forcing the tail center spindle toward the head stock, said cam means being retrogressive at all but one point in each rotation of said rotating head member backing said head center spindle toward said head stock at the same rate that the head and tail stocks are moving relative said grinding wheel whereby the cutter is held with a circumferential file in a fixed plane relative the grinding Wheel, and the cam means at said one point in each rotation having a sharp rise moving the head center spindle a progression equal to the advancement of the head and tail stocks relative the wheel during the rotation and equal to the space between circumferential files.

2. The subject matter of claim 1 in which said annular cam means includes an annular cam secured in the end of said housing opposite to the tail stock and a cam follower secured to said head spindle and disposed in said housing in position to engage said cam.

Cam plates 64 3. The subject matter of claim 1 in which said rotating head member in said head stock includes a hollow tubeshaped member extending substantially through said head stock, the housing being circular in cross-section and being secured in said tube-shaped member by a relative taper therebetween, said head spindle extending beyond said housing to the outer end of said tube-shaped member, and said connecting means between said head spindle and said head stock being a lateral arm secured at one end to said head spindle and having its other end slidably retained in a bifurcated bracket on the head stock, said lateral arm having a joint for forceable moving of the arm to engage in and withdraw from the bifurcated bracket during positioning of the serration cutter.

4. Means for adapting a thread grinder to grind a serration cutter in which teeth disposed in a plurality of rows are oriented in circumferential files substantially at right angles to the cutter axis, the thread grinder being normally adapted to grind helical threads by rotation of a workpiece between head and tail stock center spindles by means connected to a rotating head member while the head and tail stocks and a grinding wheel have relative movement whereby the workpiece is advanced laterally of the wheel periphery, said head center spindle being slidably mounted in said rotating head member and means connecting between said head spindle and said head stock holding said head spindle against rotation, cam means acting between means connected to said rotating head member and means on said head spindle, said cam means being retrogressive at all but one point in each rotation of said rotating head member backing said head spindle toward said head stock at the same rate that the rotating head member and tail stock are moving relative said grinding wheel whereby the cutter is held with a circumferential file in a fixed plane relative the grinding wheel, and said cam means at said one point in each rotation having a sharp rise moving the head spindle a progression equal to the advancement of the rotating head member and tail stock relative the wheel during the rotation and equal to the space between circumferential files.

5. Means for adapting a machine, normally used to remove material in a helical path on a threaded body or thelike, to cut a serration cutter in which teeth disposed in a plurality of rows are oriented in circumferential files substantially at right angles to the cutter axis, the machine normally rotating a workpiece between head and tail stock center spindles by a rotating member in one of said stocks while the head and tail stock spindles and a cutting means have relative movement whereby the workpiece is advanced past the cutting means, comprising: a first of said stock center spindles being slidably mounted relative said rotating member and means connecting between said first spindle and a non-rotating portion of said machine holding said first spindle against rotation, cam means acting between means connected to said rotating member and means on said first spindle, said cam means being retrogressive at all but one point in each rotation of said rotating member backing said first spindle in a reverse direction and at the same rate that the rotating member is moving relative said cutting means whereby the cutter is held with a circumferential file in a fixed plane relative the cutting means, and the cam means at said one point in each rotation having a sharp rise moving said first spindle a progression equal to the advancement of said rotating member relative the cutting means during the rotation and equal to the space between circumferential files.

References Cited in the file of this patent UNITED STATES PATENTS 2,321,421 Rickenmann June 8, 1943 FOREIGN PATENTS 885,522 Germany Aug. 6, 1953 

